1. Field of the Invention
The present invention is generally related to a method of making vitamin K1, and more particularly to a method of making vitamin K1 without metal oxidant.
2. Description of the Prior Art
Vitamin K is also called as antihemorrhagic vitamin. In 1929, it is found that there are two forms, K1 and K2, of vitamin K in the natural.
There are many researches of making vitamin K1 in the prior art. For example, in U.S. Pat. Nos.2,683,176 and 2,325,681, the vitamin K1 is obtained from 2-methyl-1,4-naphthohydroquinone as the starting material. 2-methyl-1,4-naphthohydroquinone is also used as the starting material in many literatures, such as J. Am. Chem. Soc., 1940, 62 (10), pp 2861-2866, J. Am. Chem. Soc., 1939,61, 3467-3475, Agr. Biol. Chem., 1965, 29, 978-983, and J. Am. Chem. Soc., 1937, 59(2), 392. However, it is known that 2-methyl-1,4-naphthohydroquinone is easily to be oxidized and very unstable. Therefore, there will be by-products formed during the manufacturing and the yield of the manufacturing will be decreased.
Moreover, in many literatures, metal oxidant is usually used in the manufacturing of vitamin K1, such as J. Am. Chem. Soc., 1940, 62 (10), pp 2861-2866, and Agr. Biol. Chem., 1965, 29, 978-983. It should be noticed that antihemorrhagic vitamin is possible be used on an emergently clinical patient, and the metal residue in the antihemorrhagic vitamin could be toxic and fatal to the emergently clinical patient.
In view of the above matters, developing a novel method of making vitamin K1 having the advantage of efficiently decreasing by-product formed during the manufacturing and no metal oxidant used in the manufacturing is still an important task for the industry.